Surgical drain with sensors for monitoring fluid lumen

ABSTRACT

Devices and methods of using a surgical drain, and more particularly to a surgical drain having at least one sensor for monitoring and/or recording the condition of the anatomical site or fluid emitted from the site where the surgical drain is placed. Modifications may be made to the surgical drain to improve stabilization or immobilization in the proximity of the anatomical site to be monitored.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Applications60/445,714, filed Feb. 7, 2003, No. and 60/453,009, filed Mar. 6, 2003,and incorporates the contents in their entirety. This application isalso related to the following co-pending applications, being filedcontemporaneously herewith: “Surgical Drain with Sensors for MonitoringInternal Tissue Condition,” “Surgical Drain with Sensors for MonitoringInternal Tissue Condition by Transmittance,” “Surgical Drain withSensors for Monitoring Fluid in Lumen,” and “Surgical Drain withPositioning and Protective Features,”.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention is directed to devices and methods of using asurgical drain to monitor internal tissue condition, and moreparticularly to a surgical drain having at least one sensor formonitoring the condition of a tissue proximate to the surgical drain.

2. Description of Related Art

It is desirable for a physician to know the condition of tissues ororgans (hereafter referred to interchangeably) within the patient's bodyparticularly after trauma or surgical manipulation. Since such tissuesmay reside under the skin or within a body cavity, a physician mustinvasively inspect the tissue (such as by surgery, includinglaparoscopy), or use indirect measures to assess an organ's condition(such as radiological, blood testing and patient accounts of sensationsof illness or pain). However, these methods can be disadvantageous. Aninvasive examination may cause discomfort and risk of infection to thepatient, and the information obtained either through direct inspectionor indirectly via blood or radiological analysis, may be relevant onlyto the time at which the procedure is performed, and examination mayrender only indirect information about the physiological condition ofthe organ.

Monitoring of organ function can be important after surgeries such asorgan transplantation, resection, cryosurgery and alcohol injection.Surgical complications, such as vascular complications, may disruptadequate oxygen circulation to the tissue, which is critical to organfunction and survival. Following liver surgery, for example, a physicianmay draw patient blood to determine the condition of the organ bymeasuring liver enzymes (such as transaminases) and clotting factors(such as prothrombin). Unfortunately, these blood tests reflect livercondition only at the time the blood sample is drawn, and changes inthese laboratory values can often be detected only after significantorgan damage has already occurred, permitting a limited opportunity forintervention by the physician to improve the condition of the organ orfind a replacement organ in case of transplantation for the patient.

Other methodologies have been used to assess internal tissue conditions.For example, (1) imaging and Doppler techniques, (2) optical techniques,and (3) thermodilution have been used to measure tissue oxygenationand/or perfusion. However, these techniques can be difficult tosuccessfully apply to continuous monitoring of organ condition, and mayprovide only qualitative or indirect information regarding a condition,and/or may provide information about only a small segment of an organ.

Imaging and Doppler Methods. Angiography may be used for determining thelocation and extent of blood flow abnormalities in major hepaticvessels, such as hepatic artery or portal vein stenoses and thromboses.Similarly, Doppler sonography may be used for the evaluation of bloodflow in the hepatic artery and the portal vein. These methods can lackthe sensitivity and the resolution necessary for assessing hepaticmicrocirculation. Contrast sonography has been applied for qualitativeassessment of blood perfusion in the microvasculature, but its potentialfor quantitative measurement is still unclear. Although sonography canbe performed at bedside, it is neither sensitive nor specific, and doesnot indicate the actual tissue oxygenation. It is usually used as ascreening for the more invasive angiography. Angiography is still apreferred clinical standard in determining vessel patency for any organsuch as blood flow abnormalities in major hepatic vessels, such ashepatic artery or portal vein and may visualize stenosis or thrombosisin these and other vascular structure. This test however is invasive andrequires the injection of contrast material with its side effect ofallergic reaction, kidney failure and fluid overload. The test cannot beperformed at bedside (as in Doppler Ultrasonography) and requires movingcritical ill patient to the radiology suite, and the side effects arealso higher in these sick patients.

Other imaging methods, such as Spiral Computer Tomography (CT),three-dimensional magnetic resonance, angiography and radionuclidescintigraphy using Technetium 99m sulfur colloid may be used to assessblood flow to organs such as the liver following liver transplantation.However, these methods may not be sufficiently sensitive to obviateangiographic assessment, as described above. Further, these methods canalso be limited in their ability to measure blood perfusion inmicrovasculature of the tissue. Although blood may be circulating tolarge vessels, it is oxygenation and perfusion at the capillary level,which often maintains the health of the entirety of the organ. By thetime larger vessels are visibly impaired, the organ may have alreadyundergone significant tissue damage. Further, these methods may beinvasive in requiring the infusion of dye to which patients may react.Finally, for each dye injection, the organ condition may be assessed fora given interval. If further monitoring is needed, additional dyeinjection and repeated imaging may be required.

Laser Doppler flowmetry (LDF) has been used to measure blood flow in thehepatic microcirculation, but may not be able to provide informationabout the tissue oxygenation or blood content. LDF is also limited inits application due to the short depth of penetration and the largespatiotemporal variations of the signal obtained. Therefore, thistechnique may not reflect information regarding a broad geography of thetissue, and large variations may occur in recordings from differentareas, in spite of tissue conditions being similar between the regions.

Thermodilution. Thermodilution technology has also been used formonitoring tissue perfusion. One example is the Bowman perfusionmonitor, which uses an invasive catheter probe to measure hepaticperfusion. The probe may be inserted into the liver and a thermistor inits tip may be heated to remain slightly above tissue temperature. Thelocal perfusion may be estimated from the power used in heating thethermistor to few degrees above tissue temperature to induce localdilation of the blood vessels. This can lead to a false perfusionmeasurement that is higher than the actual perfusion away from theprobe. The latter source of error may not be corrected by calibrationbecause the degree of vasodilation per temperature rise may vary betweenpatients and may depend on many factors including administered drugs.

Thermodilution techniques may also be disadvantageous at least inrequiring the insertion of catheter probes into an organ, which canbecome impractical when multiple probes are to be used.

Perfusion detection techniques such as LDF and thermodilution have anadditional common inherent limitation. These methods may not measuretissue oxygenation, which is more relevant than perfusion in determiningtissue viability. Perfused tissue can still suffer ischemia, oxygendeprivation, depending on the oxygen demand by the tissue versus itsavailability in the blood. For example, the liver has a dual bloodsupply from the hepatic artery and the portal vein. The blood flowingfrom the portal vein into the liver carries much less oxygen to thehepatic tissue than that from the hepatic artery. An occlusion of thehepatic artery would not cause a significant drop the hepatic perfusion,however, it would cause a drastic drop in the oxygenation. Hence,monitoring the hepatic perfusion only would be a misleading measure ofischemia. Further, this critical demand-availability balance can beeasily disturbed due to immunogenic and/or drug reactions, thereforemonitoring of oxygenation levels is important in monitoring tissuecondition.

Optical Methods. Conventional optical techniques for the detection oftissue ischemia include fluorescence and transmission methods. Ischemialeads to anaerobic respiration and the accumulation of the reducednicotinamide coenzyme NADH. The concentration of NADH may be detectedoptically because it is autofluorescent and has peak excitation andemission wavelengths at about 340 nm and 470 nm, respectively.Therefore, the fluorometric properties of NADH can be used to monitorand quantify this marker of ischemia.

However, this technique may not have been applied clinically due toseveral concerns. First, the fluorescence of NADH can be stronglymodulated by the optical absorption of tissue hemoglobin, and theabsorption of hemoglobin varies with its state of oxygenation, which cancomplicate the analysis of the data. These modulations can mask theactual intensity of NADH fluorescence thereby causing inaccuracies inthe evaluation of ischemia. Further, this method may be disadvantageousat least in that repeated exposure of the tissue to ultraviolet lightresults in photobleaching of the tissue. Therefore, it may not bepossible to continuously monitor the same position on the organ for aprolonged period of time (i.e., more than 24 hours). Finally, the abovemethod is only an indirect evaluation of tissue ischemia, as it relieson monitoring abnormalities in the concentration of NADH and may resultfrom other conditions such as generalized sepsis or hypotension.

Optical transmission methods involve the use of visible and/ornear-infrared radiation to measure the absorbance of blood in a tissuebed and determine the oxygen saturation of hemoglobin. A commontransmission technique is pulse oximetry where red and infrared lightfrom light emitting diodes is transmitted through the tissue, usually afinger or ear lobe, and detected by a photodiode. The oxygen saturationof hemoglobin can be estimated by measuring its optical absorption atpredetermined wavelengths that allow the maximum distinction betweenoxyhemoglobin and deoxyhemoglobin. Researchers have used lasers toilluminate one side of the kidney and detected the transmitted light onthe opposite side using a photomultiplier. For example, Maarek et al.,SPIE, Advances in Laser and Light Spectroscopy to Diagnose Cancer andOther Disease, 2135:157-165, 1994. A major disadvantage of suchtechniques is the invasive nature of the procedure to place a tissuesample between the light source and the detector for a singlemeasurement.

Intra-abdominal pressure following major surgery or trauma (such as acar accident, gun shot wounds, combat, or earthquake injuries) may riseto extremely high levels due to tissue edema secondary to the injury,especially following multiple blood transfusions, severe shock orinflammatory responses.

An increase in pressure may lead to severe organ dysfunction, such askidney failure and acute respiratory failure due to lung compressionthrough the diaphragm. The increased pressure in the abdomen may alsolead to a decrease in the venous returns to the heart, therefore,affecting the cardiac output and the perfusion to all organs/tissuesleading to a decrease in oxygen delivery.

Early detection of critical intra-abdominal pressure may be corrected byseveral interventions, including sedating the patient or opening of theabdomen. Prompt restoration of proper intra-abdominal pressure canreverse the consequences described above. However, once a critical pointis reached, organs may suddenly fail, which may be irreversible incertain conditions and lead to rapid deterioration of multiple organsand potentially death.

A current method of monitoring intra-abdominal pressure following majorsurgery or trauma relies on indirect measurement of intra-organ pressuresuch as the bladder or the stomach pressure. These methods requiredirect operator intervention and are done only intermittently at aspecific timing, such as every 1 to 4 hours, or if the patient showssigns of deterioration.

Current methods of measuring abdominal pressure may carry significanterrors due to direct personal intervention, lack of reproducibility andchallenges related to the injury itself. For example, a large hematomaor pelvic fracture may affect the bladder pressure directly withoutrelation to the overall intra-abdominal pressure.

As discussed above, each of these methods has significant technicaldisadvantages to monitoring tissue condition. Further, each of thesemethods can also be cumbersome and expensive for bedside operation dueto the size of the apparatus and cost associated with staffadministering these methods, and unsuitable for continuous monitoring oftissue conditions.

Therefore, it is desirable to have a device and methods to aidphysicians in predicting problems and complications associated withinternal trauma or surgery. It is desirable to have a device which ispositionable and removable with relatively minimal effort, minimallyinvasive and causes minimal discomfort for the patient, providescontinuous current information about tissue or organ condition, providesdirect information about tissue or organ condition, and/or providesfeedback on the effects of interventions, such as medications or otherprocedures to improve tissue or organ condition.

BRIEF SUMMARY OF INVENTION

In one embodiment of the invention, a surgical drain may be used forpostoperative monitoring of the condition of a tissue and/or organ,generally or a transplanted organ, more specifically.

In one embodiment of the invention, a surgical drain may be used toprovide continuous intraoperative and/or postoperative information onthe physiological condition of a tissue including perfusion and/oroxygenation.

In one embodiment, a surgical drain may be configured for ease ofapplication by a physician, as well as ease of removal when monitoringis no longer required.

These, as well as other objects, features and benefits will now becomeclear from a review of the following detailed description ofillustrative embodiments and the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a schematic diagram of one embodiment of a surgical drain inuse having at least one sensor; FIG. 1B is a schematic diagram depictingone embodiment of a surgical drain; FIG. 1C is a schematic diagram ofone embodiment of the surgical drain in use having a plurality ofsensors.

FIGS. 2A & B are each schematic diagrams each of one embodiment of theinvention.

FIGS. 3A-F are schematic diagrams depicting views of embodiments of thesurgical drain according to the invention. FIGS. 3A-F are bottom viewsof embodiments of a surgical drain; FIGS. 3D & E are end views ofembodiments of a surgical drain.

FIGS. 4A & B are schematic diagrams each of a side view of oneembodiment of a surgical drain.

FIGS. 5A & B are schematic diagrams of a top and bottom plan view of oneembodiment of a surgical drain, respectively; FIG. 5C is a schematicdiagram depicting a cross-sectional view of one embodiment of a surgicaldrain.

FIG. 6A is a schematic diagram of a side view of one embodiment of asurgical drain; FIG. 6B is a schematic diagram depicting across-sectional view at A-A of the embodiment shown in 6A.

FIG. 7 is a schematic diagram of one embodiment of a surgical drain inuse.

FIGS. 8A & B are a schematic diagrams each of an alternate embodiment ofa multifiber connector.

FIG. 9 is a schematic diagram of one embodiment of a surgical drain withwireless connectivity.

FIG. 10 is a flow diagram of one embodiment of a monitoring system ofthe invention.

FIG. 11 is a schematic diagram of one embodiment of a multiplexercircuit.

FIGS. 12A-E are schematic diagrams each depicting one embodiment of adisplay.

FIGS. 13A & B and 13E & F are schematic diagrams of cross-sectionalviews of embodiments of surgical drains having an inflatable chamber.FIGS. 13C & D are schematic depictions of side views of one embodiment asurgical drain having an inflatable chamber and inflation devices. FIG.13G is a graphic representation of reflectance intensities received fromthe sensing system.

FIG. 14A is a schematic depiction of a bottom view and FIG. 14B is aschematic depiction of a side view of one embodiment of a surgical drainhaving protrusions thereon.

FIGS. 15A-F are schematic diagrams of embodiments of surgical drainsmodified to improve stability of the drain relative to the tissuemonitored.

FIG. 16 is a modified distal end of a fiber collecting or receivingenergy of one embodiment of a surgical drain.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1A is a schematic diagram depicting one embodiment of a surgicaldrain in use having at least one sensor. As shown in FIG. 1A, the devicemay include a surgical drain 10 configured for implantation within thepatient's body proximate to a tissue and/or organ 100 of interest havingat least one sensor or receiver 12.

The surgical drain 10 may include one or a plurality of sensors 12 incommunication with a monitor 14, such as via a data cable 16. Themonitor 14 may also include a display 18 configured to depictinformation obtained from the sensor 12. The surgical drain 10 may be incommunication with a tube 40 having a conduit lumen 42, such that thefluids passing from the body in the drain lumen 32 may be transportedout of the body 102 via the conduit lumen 42. The tube 40 may be formedintegrally or as separate piece attached to the surgical drain 10.

FIG. 1B is a schematic diagram depicting one embodiment of a surgicaldrain 10. As shown in FIG. 1B, the surgical drain 10 may have a drainlength 20, extending from the drain distal end 22 to the drain proximalend 24. The surgical drain 10 may have an outer surface 26 and a draininner surface 28 and a drain wall 30 extending from the drain outersurface 26 to the drain inner surface 28. The drain wall 30 may be inany cross-sectional shape, such as rectangular, round, oval. Thesurgical drain 10 may include a drain lumen 32 extending the drainlength 20, and the drain lumen 32 may be open or closed at the draindistal end 22. The surgical drain 10 may include at least one or aplurality of drain holes 34 extending through at least one location onthe drain wall 30. The surgical drain 10 may include approximately adrain upper surface 36, and a drain lower surface 38, and may includedrain holes 34 on the drain upper surface 36 and/or lower surface 38.

A surgical drain 10 may be in the form of an elongated conduit and aflexible drain wall 30, having a substantially flat cross section havingat least one internal rib 128 as shown in FIG. 5C) within the drainlumen 32, and a pattern of drain holes 34 along at least a portion ofthe drain length 20, such as along at least half of the drain length oralong the entire drain length 20. The conduit may be in the form of alinear conduit or any shape, including but not limited to circular,square or triangular form.

An internal rib 128 may act to prevent the drain wall 30 from collapsinginto the drain lumen 32 even when the surgical drain 10 is subject to avery high vacuum and/or strong lateral compression forces due to bodymovements of the patient and the healing process at the drainage site.An internal rib 128 may also wipe back and forth across the oppositedrain wall 30 to keep the conduit lumen 32 and drain holes 34 clear whenthe drain walls 30 are moved laterally relative to one another. Aninternal rib may extend partially into the drain lumen (as in FIG. 5C)or across the entire lumen (as in FIG. 6B), for example.

The surgical drain 10 may be made of any material suitable forimplantation within the body 102. The material may be selected so as tobe minimally allergenic, for example. A surgical drain 10 which may beused in this invention may include a standard surgical drain. By way ofexample, the surgical drain 10 may be of a biocompatible silicone, latexrubber, polyvinyl chloride (PVC) or teflon of any color, and may beentirely or partially transparent. This may be advantageous in thattransmitting and receiving elements may be positioned within the drainwall. In one embodiment, the optical fibers 44 may transmit light to afiber distal aperture proximal to the surgical drain 10 and irradiate atissue 100, and a second optical fiber distal aperture may collect thereturned light via an optically transparent window in the drain wall 30.

FIG. 1C is a schematic diagram depicting one embodiment of a surgicaldrain 10 in use having a plurality of sensors 12. The surgical drain 10may include electrical transmitters and/or sensors, and/or fiberoptictransmitters and/or sensors. A corresponding wire or fiber from eachsensor 12 may run along the drain length 20 and exit the surgical drain10 as a data cable and/or multi-fiber bundle 16 that couples the sensor12 to a monitoring system 14. Examples of connectors 62 which may beused to couple the sensor to the monitoring system are described withreference to FIGS. 8A & B below.

FIGS. 2A & B are schematic diagrams of each of one embodiment of theinvention. The surgical drain 10 may include at least one or a pluralityof sensors 12. As shown in FIG. 2A, the surgical drain 10 may include aplurality of sensors 12 spaced along the drain length 20 to permit themonitoring of different locations of a tissue 100 A, B & C to bemonitored. As shown in FIG. 2B, the surgical drain 10 may have aplurality of drain branches 10 a/b to accommodate monitoring largerwounds, tissue beds or tissues 100. Finally, in one embodiment, aplurality of separate surgical drains 10 may be used to monitor a singleorgan or a plurality of organs 100 at the same time.

The surgical drain may include a sensing system configured to sense aphysiological property of a tissue 100 proximate to a surgical drain 10.In some embodiments, the sensing system may include sensors 12 which arepositioned proximate to the surgical drain 10 and tissue. In someembodiments, transmitting elements 48 and receiving elements 12 may beconfigured to deliver energy and receive energy, for transmission toanother portion of the sensing system to sense a physiological propertyof a tissue. The energy may include, but is not limited to, light, heatand ultrasound. It is to be understood that sensor 12 may refer toeither a sensor, such as an electrical sensor, or a receiving elementsuch as a fiberoptic proximate to the surgical drain 10. The sensors 12may be positioned proximate to a tissue 100 for which monitoring isdesired, and the sensors 12 may be configured to receive and/or detectparameters regarding the condition of the tissue 100, fluid proximate tothe tissue or flowing into the surgical drain 10 therefrom. The surgicaldrain 10 may include at least one sensor 12 in contact with the surgicaldrain 10. For example, the sensor 12 may be on the drain outer wallsurface 26, drain inner wall surface 28 or within the drain wall 30. Thedrain wall 30 may be modified to include a groove 46 to accommodate thesensors 12, transmitter 48 and/or wires/fibers 44 extending therefrom.

The sensor 12 may be situated such that at least a portion of the sensor12 is in contact with the monitored tissue 100 or in proximity to thetissue 100, or in contact with interstitial fluids therefrom so as toprobe the condition of the adjacent tissue.

A sensor 12 may be configured to detect physiological parameters, whichpermit the measurement of tissue oxygenation, perfusion, haemoglobincontent, color, temperature, pressure, pH, respiratory coenzymes (suchas NADH), local exogenous drug levels, mechanical properties (such asturgidity) and biochemical composition of the fluid within the surgicaldrain (such as hemoglobin, puss, bile, intestinal contents, etc.).

By way of example, pH sensors 12 may be used to detect changes in ionconcentration in fluids surrounding a tissue 100 or within a drain lumen32. For examples of pH sensors that may be useful in this invention, seeU.S. Pat. No. 5,916,171 to Mayviski, herein incorporated by reference.

In one embodiment, a temperature sensing system may be used to detectthe temperature of a tissue 100. For example, a fiberoptic thermometermay be used. The fiberoptic may transmit an excitation light pulse tothe fiber distal end in proximity to a tissue 100, causing it tofluoresce. The fiber distal end may include a nonconductive phosphortip. The fluorescent signal may be transmitted back to a photodetectorby the same fiber. The fluorescent decay time may be measured by amultipoint digital integration decay curve, used to correlate the decaycurve with a temperature value.

In one embodiment, a pressure sensing system may be used to detect thepressure within a body cavity, such as the abdominal cavity. Forexample, a fiberoptic pressure sensor may be used, and may include apressure sensing element such as an optical interferometer at a distaltip of a fiber, and interferometric integration may be used to sense andmonitor pressure over time. For examples of integration methods, seeU.S. Pat. Nos. 5,392,117 and 5,202,949, herein incorporated byreference.

FIGS. 3A-F are schematic diagrams depicting views of embodiments of thesurgical drain according to the invention. FIG. 3A depicts a bottom viewof one embodiment of a surgical drain 10 including at least one sensor12 proximate to the drain lower surface 38. The surgical drain 10 mayfurther include at least one transmitter 48 for delivering energy, suchas light, including white light, to the monitored tissue 100, in theproximity of the at least one sensor 12. The surgical drain 10 mayfurther include a plurality of pairs of transmitters 48 and sensors 12located along the surgical drain length 20 so as to detect informationfrom different regions of the organ 100, as shown in FIG. 1C, forexample.

By way of example, as shown in FIG. 3A, a sensor 12 in proximity to atransmitter 48 may be used to collect derived energy, including thereflectance or diffuse reflectance from, or transmitted energy throughthe tissue 100 monitored.

FIG. 3B depicts a bottom view of one embodiment of a surgical drain 10including at least one sensor 12 positioned in a groove 46 formed in thesurgical drain wall 30. The surgical drain 10 may further include atransmitting element 48, and/or at least one or a plurality of drainholes 34 along the drain length 20.

FIG. 3C depicts a bottom view of one embodiment of a surgical drain 10including at least two sensors 12 a/b, spaced at a distance from atransmitter 48 on the drain lower surface 38. In one embodiment, theconfiguration may be used such that at least one transmitter 48transmits energy and the sensors 12 a/b receive derivative energy todetect different physiological parameters of the tissue 100, such asperfusion, oxygenation and temperature. The configuration may be used tomeasure the same parameter, and may permit the measurement of energyattenuation over distance between the transmitter 48 and the sensors 12a/b.

FIG. 3D depicts an end view of one embodiment of a surgical drain 10including at least one sensor 12 positioned within the drain wall 30.This configuration may allow the positioning of longer sensors in thedrain wall and may avoid the need for thicker drain walls. In addition,this configuration may allow a farther placement of a sensor 12 from atransmitter 48 to avoid saturation. This may be a particularly usefularrangement when using high output (e.g., luminance) transmitters fordeeper range detection. Positioning of sensors 12 in different areas ofthe drain wall 30 may permit the collection of information from avariety of tissue locations 100. Information from each location may becompared to obtain differential parameter measures.

FIG. 3E depicts one embodiment of the surgical drain 10 which mayinclude at least a pair, including a transmitting element 48 and asensor 12 positioned at different positions of the drain wall 30, suchas within approximately opposite sides of the drain lumen 32. In oneembodiment, the transmitting element 48/sensor 12 pair may act as an insitu spectrophotometer to detect substances within the drain lumen 32between the transmitting element 48/sensor 12. Variation of thecomposition of fluid along sequential pairs of sensors 12 along thedrain length 20 may yield information about the source or condition ofthe fluid. For example, the wavelength dependent attenuation oftransmitted radiation by the fluid flowing in the drain lumen may beused to determine whether blood, puss, bile, intestinal contents, and/ora mixture of all are present, according to standard spectrophotometrictechniques. The contents of the drain lumen may be is indicative of thecondition, including the healing progress of the tissue.

FIG. 3F depicts one embodiment of the surgical drain 10, which mayinclude at least one sensor 12 positioned at least partly within thedrain lumen 32. In one embodiment, the sensor 12 may act to detect thecomposition or the mechanical properties of fluid flowing in thesurgical drain lumen 32.

FIG. 4A is a schematic diagram depicting a side view of one embodimentof a surgical drain 10, which may include a sensor 12 embedded in thedrain wall 30 and a transmitting element 48 to be inserted into theorgan 100. The sensor 12 and transmitting element 48 may be fiberopticor electrical, and the distal ends of each may be oriented such thatenergy emitted from the transmitting element 48 may be substantiallyreceived by the sensor 12. For example, as shown in FIG. 4A the sensordistal end 12 may terminate at a perpendicular to the surgical drainouter surface 26 and the transmitting element distal end 48 may beangled such that the sensor receives energy emitted from thetransmitting element 48 distal end. In one embodiment, the distal end ofthe sensor 12 and the transmitting element 48 may be coaxially aligned.In one embodiment, the surgical drain 10 may include a transmittingelement 48 embedded in the drain wall 30, and a sensor 12 to be insertedinto the organ 100. In one embodiment, a housing 50 with a housing lumen52 may be opposed to or encompass the transmitting element 48 or sensor12 that is being inserted into the organ 100 to provide structuralsupport. The housing 50 with a housing lumen 52 may be a hollow needlemade of a biologically compatible material. The housing 50 mayadvantageously serve as an anchor to attach and/or immobilize thesurgical drain 10 relative to an organ 100.

FIG. 4B is a schematic diagram depicting a side view of one embodimentof the invention, which may include optical transmission sensorscomposed of two needle shaped fiberoptics 12/48 for insertion into amonitored tissue 100. For example, as shown in FIG. 4B the transmittingelement distal end 48 and sensor distal end 12 may be angled such thatthe sensor 12 receives radiation emitted from the transmitting element48. In one embodiment, the transmitting element 48 and sensor 12 mayeach be opposed to or encompassed by a housing 50 with a housing lumen52 to provide structural support. The housing 50 with a housing lumen 52may be a hollow needle made of a biologically compatible material. Thehousing 50 can advantageously serve as an anchor to attach andimmobilize the drain 10 on the organ 100.

As shown in FIG. 16, in one embodiment, to enable a fiber to irradiateenergy at about 90 degrees, the fiber distal end may be polished atabout a 42-degree angle (α) to its axis. Further, glass ferrule caps maybe placed over the polished end. In use, the light may be reflected onthe polished end, and be emitted at about 90 degrees to the fiber axis132.

In one embodiment, a fiber collecting or receiving energy may beprepared using a similar process.

In these configurations, for example, light emitted from a transmittingelement 48 may be transmitted through a tissue thickness 54 to a sensor12. Using standard transmission, reflection and/or fluorescencespectroscopy techniques, the transmitted light may be used to measurephysiological information including, but not limited to tissueoxygenation, perfusion, coloration, and drug concentration.

FIGS. 5A & B are schematic diagrams depicting a top and bottom plan viewof one embodiment of a surgical drain 10. Optical fibers and/or the leadwires 44 that may connect the sensors 12 and the transmitters 48 may beevenly distributed along the drain surface lengthwise to prevent themechanical twisting of the drain wall 30. This may be advantageous atleast to maximize contact between the sensors 12 and the tissue 100.

FIG. 5C is a schematic diagram depicting a cross-sectional view of oneembodiment of a surgical drain 10. In one embodiment of the invention,the surgical drain 10 may include at least one pair of sensors 12 a/bpositioned approximately on opposite sides of the drain wall 30. Thesurgical drain 10 may also include a plurality of pairs of sensors 12a/b, 12 c/d, 12 e/f positioned at different locations along the drainlength to detect information from different positions along the drainlength 20, such as shown in FIG. 6A.

FIG. 6A is a schematic diagram of a side view of one embodiment of asurgical drain; and FIG. 6B is a schematic diagram depicting across-sectional view of one embodiment of a surgical drain. In oneembodiment of the invention, the surgical drain 10 may include at leastone pair of sensors 12 a/b positioned proximate to different surfaces ofthe surgical drain 10. The surgical drain 10 may also include aplurality of pairs of sensors 12 a/b, 12 c/d, 12 e/f positioned atdifferent locations along the surgical drain length to detectinformation from different positions along the drain length 20.

As shown in FIG. 6B, in one embodiment, the surgical drain 10 may have adrain width 56 of about 15 mm, and a drain height 58 of about 6 mm, adrain length 20 of about 200 mm, a drain hole diameter 34 of about 1.5mm, and a drain lumen height and width of about 4 mm. The surgical drain10 may include a plurality of lumens 32; and fibers/wires 44 to and/orfrom the transmitting elements 48 and/or sensors 12 may be orientedwithin the surgical drain 10, such as in an internal rib 128. In oneembodiment, a sensor 12 may be embedded in the drain wall 30. This maybe advantageous at least in facilitating the use of additionalmodifications to drain wall 30 or outer surface 26, such asstabilization devices and mechanisms for increasing contact betweentissue and sensors, described below.

FIG. 7 is a schematic diagram depicting one embodiment of a drain inuse. In one embodiment, sensors 12 may be placed on opposite sides orproximate to sides of the surgical drain 10 such that the sensor pairs12 a/b may be used to acquire differential measurements betweendifferent organs/tissues positioned in the proximity of sensors pair 12a/b. For example, as shown FIG. 7 a surgical drain 10 may be positioned,such that the drain lower surface 38 is proximate to an organ to bemonitored 100, and the drain upper surface 36 is proximate to anadjacent tissue. Therefore, sensor pairs 12 a/b may be positioned tomeasure a parameter differentially between the monitored organ 100 andthe adjacent tissue. These differential measurements may improve theaccuracy of the measurements/diagnosis, such as in monitoring forcomplications in hepatic perfusion. For example, a lower than normaloxygenation of the liver may not be indicative of problems in thehepatic perfusion because the oxygenation of the whole body may be lowerthan normal due to respiratory and/or circulatory problems. However, ifthe oxygenation levels of the liver are lower than normal while theadjacent tissues are at normal oxygenation levels, then this is a realindication of reduced hepatic perfusion.

Any type of sensors (such as oxygenation, perfusion, pH, temperature,color) may be used in a differential mode measurement, such as describedabove. The sensor 12 type used may be selected so as to maximize thedetection of the desired physiological parameter, maximize biologicalcompatibility with the patient's tissues or other components of thedevice, and to minimize any risk of electrocution or the like.

In one embodiment, the device may be configured to detect the color ofan organ 100. The surgical drain 10 may use a single fiber, or mayinclude at least one transmitting element 48 and at least one sensor 12.The transmitting element 48 may be a fiberoptic 44 having a distal endconfigured to deliver light from a light source to the organ 100. Thelight may be reflected from, diffusely reflected from or transmittedthrough at least a portion of the organ 100 in the proximity of thetransmitting element distal end 48. The sensor 12 may be a fiberoptic 44having a distal end configured to collect light having a spectralpattern reflected, diffusely reflected or transmitted through the organ100, and transmit the spectral pattern to a photodetector or processingsystem 80. The color may be extracted from a wavelength spectrum usingstandard wavelength to RGB conversion techniques.

The oxygenation of an organ may be determined by measuring theoxygenation of the hemoglobin within a tissue. The spectralcharacteristics of hemoglobin are dependent on its state of oxygenation.The oxygenation of the organ 100 may be determined by measuring thespectral characteristics of hemoglobin using a similar sensor 12, asdescribed above.

The monitoring system 14 may include a processing system 80 forconverting the spectral pattern information to a color, which may bepresented to a physician on a display 18. The processing system 80 mayalso convert the spectral pattern information to a color index number,which may be presented to a physician on a display 18. The system mayalso include data of normal colors and color indexes for automatic ormanual comparison so that a tissue abnormality may be noted.

Determining the physiological conditions, such as color and/or colorindex of the tissue, may be advantageous at least in that the physicianmay determine from the color of the tissue the general health of thetissue, including whether the tissue is adequately oxygenated and/orjaundiced. Further, the monitoring function is advantageous in that itmay be continuous or at intervals selected. Further, the monitoringfunction is advantageous in that is may be minimally invasive and doesnot require opening the patient to assess the tissue condition.

In one embodiment, diffuse reflection may be used to determine theoxygenation level of at least a portion of an organ 100. This method maybe advantageous at least in that information about the internal portionof the organ 100 may be obtained, without penetrating the surface of thetissue with a sensor 12 or a transmitting element 48.

In one embodiment, the device may be configured to detect thetemperature of the monitored organ 100. In one embodiment, the devicemay include a fiberoptic temperature sensor as described above inproximity to the surgical drain 10. The temperature sensor 12 maytransmit the light for information processing. A processing system 80may convert the phosphorescence decay-time to a temperature value whichmay be presented to a physician on a display 18. The system may alsoinclude data of normal temperatures for automatic or manual comparisonso that an abnormality may be noted. Determining the temperature of theorgan 100 is advantageous at least in that the physician can determinefrom the temperature the general health of the tissue including whetherthe tissue is being properly perfused after transplant as improperlyperfused tissues may decrease in temperature, for example. A temperaturesensor 12 may be of any type other than fiberoptic includingthermistors, thermocouples and resistance temperature detectors (RTD's),for example.

The system may acquire simultaneous differential measurements from alongthe drain length or between the different tissues between which thesurgical drain 10 is positioned. Measurement of a given parametersimultaneously from adjacent normal organs/tissues (e.g., abdominalwall) and from the organ/tissue of interest suffering problems (e.g.,the liver) can provide a control or reference value. This control orreference value can be used as a comparison factor to improve theaccuracy of the parameter measured from the organ/tissue of interest100.

In one embodiment, the device may be configured to detect therespiratory coenzyme NADH levels from the monitored organ 100.Fluorescence spectroscopy may be used to measure the fluorescence ofNADH which has a peak emission at 470-nm and to detect its concentrationin the tissue 100.

In one embodiment, the device may be configured to detect concentrationsof exogenous drugs within the tissue 100 or fluid in the drain lumen 32.For example, drugs (such as chemotherapeutic agents) may auto-fluoresceor may be coupled with a fluorescing tag having a selected peakemission, which may be detected by fluorescence spectroscopic methods.

In one embodiment, the device may be configured to detect pressure. Inone embodiment, the surgical drain 10 may include fiberoptic pressuresensors as described above.

The surgical drain 10 may include at least one or a plurality of sensors12 in communication with a monitoring system 14, such as via a datacable 16, such as shown in FIG. 1A. Wires and/or fibers 44 may bebundled together towards the surgical drain 10 proximal end and exit thesurgical drain 10 within a sheath.

In one embodiment, the surgical drain 10 may include optical fibers 44a/b and a multifiber connector 62 may be an optical fiberopticconnector, which joins each fiber 44 a to a complementary fiber 44 b inthe monitoring system 14 to establish optical continuity. FIG. 8A is aschematic depicting a side view of one embodiment of an opticalconnector 62 that may be constructed to minimize the distance betweenthe apertures of the corresponding optical fibers 44 a/b. The regionwhere the fiber apertures meet may be filled with an index-matchingsubstance 64, such as optical gel to optimize the optical continuitybetween the corresponding fibers 44 a/b. The optical gel may fill theair gap between corresponding optical fibers and hence improve lighttransmission by decreasing the back reflection that may occur at an airinterface due to mismatch in the refractive index. The connector 62 maybe configured so as to have a complementary shape to a receptor 66. Theconnector 62 and receptor 66 may include complementary locking members68 a/b to maximize the meeting of the apertures of the correspondingoptical fibers and prevent inadvertent separation between thecomponents.

FIG. 8B is a schematic depiction of one embodiment of a multifiberconnector 62, which may be used in a surgical drain 10 including lightsources 60. In one embodiment, at least one light emitting diode (LED)may be used as a light source 60, such as when low power consumption isdesirable. The LED may be of the white, multi-wavelength, ormonochromatic type. An LED-block 70, such as shown in FIG. 8, may beused to couple at least one LED to a transmitting element 48, such as anexcitation optical fiber 44 and hence minimize light losses at themultifiber optical connector 62. In one embodiment, electricalconnectors 72 may be used to drive LEDs 60 in a LED-block 70, while theoptical connectors 74 may be used to guide the collected optical signalsfrom sensors 12 to a monitoring system 14.

FIG. 9 is a schematic diagram depicting one embodiment of a surgicaldrain with sensors and wireless connectivity. In one embodiment, thedevice may include a monitor 14 in communication with the sensors 12 ofthe surgical drain 10. The monitor 12 may be directly affixed to the endof the surgical drain 10 and/or tube 40, and may utilize an antenna 78to receive command signals to activate transmitting elements 48 and/ortransmit data obtained from the sensors 12 to a receiver 76. If themonitoring system 14 includes an antenna 78, the antenna 78 may bepositioned such that it runs longitudinally along the drain tube 40.

In one embodiment of the invention, the device may comprise a surgicaldrain 10 in communication with a monitoring system 14 that may include aprocessing system 80, a display 18, device(s) to drive the frequencyand/or magnitude of signals to transmitting elements (such as a lampmultiplexer 82) and/or receive and detect information from sensors 12and/or a device to record information from a sensor 12 associated withthe surgical drain 10 overtime. The monitoring system 14 may beconfigured so as to continuously obtain information regarding thecondition of the organ or obtain information only at preselectedintervals or on demand from a physician. In one embodiment of theinvention, the monitoring system may include a recorder 108. Therecorder 108 may store acquired information for later retrieval andreview. The recorder may be a hard disk of a processor or computer.Extended history (e.g., 7 days) of a given physiological parameter maybe stored and later retrieved from the recorder, and displayed ifdesired. The processor 80 may include signal-processing algorithms toautomatically detect and alarm for abnormalities. In one embodiment, thesystem may include an alarm which may be triggered when an abnormalityis detected in a physiological parameter is detected (relative topre-set values) or when inadequate contact of sensors to make ameasurement. The system may include a manual preset of the alarmthreshold.

In one embodiment of the invention, the processing system 80 may processthe reflectance intensities received from the sensing system at about540, 580 and 640 nm to determine if a reflectance sensor 12 is inoptimal contact with an organ 100. FIG. 13G shows one example of thereflectance spectrum of white light from the surface of a deoxygenatedliver. Spectrum 200 may result from a reflectance sensor that is in goodcontact with the surface of the organ 100. Spectra 210, 220 and 230 mayresult from a sensor 12 that is not in contact with the organ 100. Theprocessing system may activate a pump 118 upon detection of a spectrumrepresenting poor sensing system contact such as 210, 220 and 230 or thelike. The processing system 80 may further control a pump 118 toincrementally pump a fluid (e.g., saline) volume into the inflatablechambers 114 while measuring changes in the spectrum after each pumpedvolume. The filling of the inflatable chambers 114 may push the sensor12 closer towards the organ 100. The processing system 80 may stop thiscontact ensure sequence upon the measurement of a spectrum representingoptimal sensor contact with the organ 100, such as about spectrum 200,or the like. A pressure sensor 120 may monitor the pressure output fromthe pump 118 and provide real-time feedback information to the pump 118and the processing system 80 to avoid excessive pressure that mayrupture the inflatable chamber 114. The processing system 80 maymemorize the volume pumped into the inflatable chamber 114, so that itcan be withdrawn later or repeated at a later time.

The system may be configured to permit a physician to be able to reviewpreviously recorded data simultaneously while the monitor 14 isrecording. The system may include a search feature, such that aphysician may display the data segments where selected physiologicalinformation occurs, such as periods where abnormalities were detected(e.g., hypoxia or ischemia). The system may also include an alarmfeature, selectable by the user so that the system may alert the user ifan abnormality is detected. A display 18 may include a touch-screengraphic user interface 112. For example, the graphic user interface 112may permit a user to select options, including but not limited tohistory review of the information detected for a selected parameter,review of abnormal conditions, select alarm option, freeze screenoption, trace display option, sample interval selection, display mode.In one embodiment, the physician may select an interval at whichmeasurements are obtained from the tissue. This interval may vary, forexample from about 1 to 60 minutes, such as about 5 minutes.

FIG. 10 is a schematic depiction of one embodiment of a monitoringsystem 14. In one embodiment of the invention, the monitoring system 14may include a processor 80, a display 18, a fiberoptic thermometer and aspectroscopic system. The spectroscopic system may include aspectrograph and a multiplexed light source, which may be used tomeasure parameters such as the tissue perfusion, oxygenation and color.The spectrograph, lamp multiplexer 82 and/or thermometer may beconnected to a processor 80, such as by computer interface such asuniversal serial data bus (USB), digital input/output interface card(DIO), analog to digital converter (A/D), and/or RS232 serial port.

In one embodiment, a spectrometer 88 may be used to monitorphysiological parameters at a plurality of locations of the organ 100corresponding to the sensors 12 positioned at various positions alongthe drain length 20.

FIG. 11 is a schematic depiction of one embodiment of a lampmultiplexing configuration 82. An excitation optical fiber 44 a maytransmit light from a lamp 60 to a tissue 100, while a collectionoptical fiber 44 b may collect light reflected from, diffusely reflectedfrom or transmitted through the tissue 100. The system may be configuredsuch that light is emitted from one lamp 60 a for transition via anexcitation optical fiber 44 a terminating at a first position (A) of theorgan 100 for a selected duration of time, at which time no other lamp(such as 60 b or 60 c) emits light at a second (B) or third (C) positionof the organ 100 (as shown in FIG. 2A). A counter 90 may be controlledby two signal lines (i.e., clock and rest) to multiplex the spectralacquisition from different locations relative to a tissue. In oneembodiment, a plurality of optical collection fibers 44 b may connect tothe spectrometer 88, while each of the excitation optical fibers 44 amay receive light from a separate lamp 60 a-c, respectively. Hence, thespectrometer 88 may measure the spectrum of the light received via anyof the plurality of collection fibers 44 b at a selected time. In use, asensor 12 may be in the dark (i.e., inside the body) and cross talkminimized between sensors 12, such as by positioning the sensors at asuitable distance from one another along the drain length 20.

With respect to the lamp 60, an optical filter 92 may be used to removeundesired wavelength bands such as those in the ultraviolet region. Alens 94 may be used to focus light emitted by a lamp 60 into theproximal aperture of the optical fiber 44 a. An adjustable iris (notshown) may be used to limit the light intensity to the desired levels. Avoltage regulator 96 may used to supply a constant voltage to the lamp60 and hence maintain constant irradiation levels. The processor 80 or aseparate drive may control the light on/off via its interface with themultiplexer 82.

In one embodiment, a measured spectrum of the light (such as diffuselyreflected) may be corrected for distortions caused by the dark current,ambient light and/or spectral response of the system. The spectrameasured by a spectrometer 88 may be processed by the processor 80according to the known methods of diffuse reflectance spectroscopy (ortransmission spectroscopy methods if applicable) for the measurement ofthe concentrations of oxygenated and deoxygenated hemoglobin in an organ100. The spectral classification methods may include peak ratios,artificial neural networks (ANN), multiple linear regression (MLR),principal component regression (PCR), and partial least squarestechniques (PLS).

In one embodiment, standard methods for converting wavelength to visualred, green, blue (“RGB”) may be used to regenerate a color correspondingto the spectra collected from the organ 100 for visualization on adisplay 18 of the monitoring system 14. The wavelength to colortransformation formula and the color display algorithm values may becalibrated using colorimetry techniques to ensure that the displayedcolor is visually similar to the actual color of the organ 100.

In one embodiment, spectral information obtained regarding the organ 100may be converted to a color index, such as a number for visualization ona display 18 of the monitoring system 14. A numerical color index may bedisplayed to provide the physician with a quantitative color evaluationof the organ 100. This may be advantageous at least in diagnosing tissueconditions, which affect the color of the organ 100, such as jaundiceand ischemia.

A display 18 may show information, for example in a graphical, numericalor color form to a physician of user-selected physiological parametersincluding, but not limited to, tissue oxygenation, perfusion,temperature, coloration, pH and pressure. FIGS. 12A-E are schematicdiagrams depicting one embodiment of a display 18. In FIG. 12A, forexample, the display 18 may include a screen showing at least oneselected parameter for each sensor position on the organ 100 (such as“1,” “2” or “3”) over a selected time. In this example, oxygenationlevels are shown graphically over time, and corresponding patches ofcolor are depicted on a graphical symbol of the selected organ relativeto the position of each sensor 12 along the organ 100. The color patchmay be depicted as an annulus surrounding the sensor number from whichthe color is detected. In FIG. 12B, for example, the display 18 mayinclude a screen showing a plurality of different parameters for asingle sensor position upon the organ 100 over a selected time. In thisexample, oxygenation, perfusion and temperature levels are showngraphically over time, and the corresponding patch of color is depictedon a graphical symbol of the selected organ relative to the sensor 12(e.g., “2”) for which the information is being displayed. The colorpatch may be depicted as an annulus surrounding the sensor number fromwhich the color is detected. A screen indicator may mark the sensornumber from which the displayed oxygenation, perfusion and temperaturevalues were collected. The operator may select to display the parametersset of any sensor by simply clicking on the symbol of that sensor on thetouch screen.

The physiological parameter detected by each sensor 12 (such asperfusion or oxygenation of the tissue at the location of each sensor)may be visualized on a display 18 as percentage of predetermined normalvalues. For example, the display 18 shown in FIG. 12C displays theoxygenation traces of five sensors along the drain length 20 relative toa normal value.

FIG. 12C is a schematic depiction of one embodiment of a display 18. Aphysician may select to display at least one of selected physiologicalparameters such as tissue perfusion, oxygenation, color or temperatureat each trace representative of each sensors, as shown in FIG. 12C. Thedisplay may also indicate if a sensor is not operating to collectinformation (such as in trace “4”). The display may include a user inputsuch as “Sensor Ensure” button which when activated employs the “sensorcontact ensurance system” shown in FIG. 13, if needed. The user mayselect this feature to ensure that all sensors are in good contact withtissue 100, where and when needed.

FIG. 12D is a schematic depiction of one embodiment of a display 18. Inone embodiment, the physician may select to display differentphysiological parameters measured at each sensor location, as shown inFIG. 12D. The display 18 may be configured such that multiple screenwindows may be opened to display different sensor locations at the sametime.

FIG. 12E is a schematic depiction of one embodiment of a display 18. Asshown in FIG. 12E, measured parameters include: blood content, abdominalsecretions and bile. These parameters may be measured optically usingstandard spectrophotometric techniques. Other optical and electricalsensors may be used to measure the pH and the concentration of ions inthe drained fluid, for example.

As depicted in this example, the surgical drain has three opticalsensors distributed along the drain length 20 for detecting fluid withinthe lumen at each of the locations. Using the “Display-Mode” slidebutton, a user may select to display all the parameters at a givensensor location or a single parameter for all sensors. The concentrationof each of the measured parameters may be determined and displayed as apercentage of the fluid mixture.

The display 18 may include a movable drain-shaped screen cursor that maybe freely oriented on a graphical symbol of the human abdomen to showthe physician the actual drain orientation inside the body. Thedrain-shaped cursor may be manually oriented upon the application of thedrain.

In one embodiment, it may be desirable configure the surgical drain 10to maximize the contact between a sensor 12 and the organ 100. This maybe advantageous at least in improving the accuracy of measurementsobtained from the organ 100.

FIGS. 13A & B are schematic diagrams depicting cross-sectional views ofone embodiment of a surgical drain 10. FIGS. 13B & C are schematicdepictions of side views of a surgical drain 10. In one embodiment, thesurgical drain 10 may include at least one inflatable chamber 114, suchas balloons within the body of the surgical drain 10. The surgical drain10 may further include a channel 116 in communication with the interiorof the inflatable chamber 114. In one embodiment, a pump 118 may be incommunication with the channel 116 and the interior of the inflatablechamber 114. The pump 118 may include a pressure sensor 120 incommunication with the inflatable chamber 114 may be used to control theinflation process so that the sensor 12 comes in optimal contact withthe organ 100. In one embodiment, the inflatable chamber 114 may bepositioned on the surgical drain upper surface 36 approximately oppositea sensor 12 proximate to drain lower surface 38. The inflatable chamber114 may be expanded by inflation, such as with saline, air or the likesuch that the inflatable chamber 114 would bulge out and create a force(F) against the adjacent tissue, as shown in FIG. 13C. This force maygenerate a reaction force (R) that may press the sensor 12 on the drainlower surface 38 against the organ 100.

The inflatable chamber 114 may be left continuously inflated throughoutthe monitoring period, or temporarily inflated when the sensors 12 areacquiring measurements. The processor 80 may analyze the averageintensity and/or spectral features of the reflected light measured atthe sensor to determine if the sensor 12 is in optimal contact with theorgan 100.

FIGS. 13E & F are schematic diagrams of a cross-sectional view of analternative embodiment of a surgical drain including an inflatablecompartment 114. The inflatable compartment 114 may be positioned withina central portion of the drain 10, such as within an internal rib 128.Upon inflation, forces may press the drain upper surface 36 and lowersurface 38 against tissue 100, thereby improving sensor 12 contact.

FIGS. 14A & B are schematic depictions of a bottom view and a side viewof one embodiment of a surgical drain 10. In one embodiment, sensors 12may be positioned within or upon protrusions 122 which extend from thedrain outer surface 26. The protrusions 122 may be integral to the drainbody 10 or attached thereto. The protrusions 122 may be made of atransparent material. This configuration may be advantageous inincreasing the pressure with which the sensors contact an organ 100.

In use, a surgical drain 10 may be placed within a body cavity proximateto a site of trauma or surgery. The surgical drain 10 may permit thefluid caused by tissue edema, for example, to be drained from the site.To position a surgical drain 10, a physician may, for example, create anincision through which the surgical drain may be implanted.Alternatively, if the patient has been opened for surgery, the drain maybe positioned proximate to the surgical site and the body closed aroundit. The surgical drain 10 may be positioned upon an organ or betweentissues of interest, and may be positioned such that sensors 12 contactdifferent regions of a tissue until monitoring is no longer needed, atwhich time the drain may be pulled out of the body. In one embodiment ofthe invention, one or more surgical drains 10 may be placedon/in/proximate to an organ 100 to monitor its condition and removedwhen monitoring is no longer desired, such as at the end of thepostoperative monitoring period.

In some embodiments, it may be desirable to stabilize the position ofthe drain 10 relative to the tissue, such that the sensors 12 haveimproved contact with the tissue 100 and/or to increase the likelihoodthat measurements taken over time will be of the same or similar portionof the tissue 100. Therefore, in some embodiments, the surgical drain 10may be modified to stabilize its position relative to a monitored organ100.

The surgical drain 10 may be actively attracted to the surroundingorgans/tissue by the continuous negative pressure (suction) in its lumen32. The negative pressure may also draw wound fluids from the surgicaldrain 10. External suction may be actively applied to a tube 40 incommunication with a surgical drain 10.

FIGS. 15A & B are schematics depicting a plan view and a side view of asurgical drain 10. In one embodiment, the surgical drain 10 may includeat least one anchor 124 configured for insertion into a tissue 100 tostabilize the position of the surgical drain 10 within the body. Theanchor 124 may be integral to the surgical drain 10 or may be fabricatedseparately from the surgical drain 10 and connected thereto. The anchor124 may be in the form of a biologically compatible needle, which mayinclude a beveled distal end for insertion into a tissue 100. Thedirection of the insertion into a tissue 100 may be opposite to thepullout direction of the surgical drain 10 for smoother removal from thepatient.

FIG. 15C is a schematic depicting a plan view of a surgical drain 10.The anchor 124 may be in the form of a loop 124 extending from thesurgical drain outer surface 26. In use, a surgeon may utilize the loopas a suture point to attach the surgical drain 10 to a tissue, such aswith a resorbable suture.

FIG. 15D is a schematic depicting a bottom view of a surgical drain 10.The anchor 124 may be in the form of biocompatible adhesive 124, such asmedical grade pressure sensitive adhesive, or fibrin glue for adheringthe surgical drain 10 to the surface of the organ 100.

FIGS. 15E & F are schematics depicting a bottom view and a side view ofa surgical drain 10, respectively. The anchor 128 may be in the form ofa flap 136 which extends from the drain outer surface 26. The flap 136may be integral to the drain wall 30 or formed separately and attachedthereto. The flap may be formed of the same material as the drain wall30. The material may be selected so as to permit flexibility of the flap136 as it is positioned relative to the tissue 100 or as it is removedfrom the body 102. The flap may further include a leading edge 130,which may be reinforced to provide a greater thickness at the leadingedge 130 than at the remainder of the flap 136. The shape of the flapmay be selected so as to enhance the stabilization of the drain 10relative to the organ 100, and may prevent rotation of the drain 10. Theflaps may assume any other shape including square, circular andrectangular. The flaps 136 may also include a layer of adhesive foradhering the flap to a tissue. The flaps 136 may also include sensors12, if desired.

In one embodiment, there may be flap wings 136 on both sides tostabilize the surgical drain 10 on the surface of the tissue 100. Theflap wings may increase the surface area of the drain 10 at the sensorlocation 12 and hence improve its passive adhesion to the moist surfaceof an organ. The flaps 136 may be preferably rectangular in shape withtheir apex pointing in the pullout direction of the drain 10 forsmoother removal from the patient. The flaps 136 may have edges 130 thatare reinforced against tearing by a thicker silicone layer or by anembedded thread or wire that is continuous into the drain wall 30.

Anchors 124 may be advantageous at least in preventing the surgicaldrain 10 from moving relative to the organ 100 during use. Further, theanchor 124 may also hold the sensor 12 on the surgical drain outersurface 26 against the surface of the tissue of interest 100. The formof the anchor 124 may be selected to minimize damage to the tissue ororgan to which the surgical drain 10 is attached. Further, the anchormay be selected to maximize the stability of the connection between thesurgical drain and the target organ, yet minimize the effort and damagecaused during surgical drain removal.

In one embodiment, a surgical drain 10 may be placed in the proximity ofan organ which has been transplanted, such as a liver, kidney, such thatthe drain length 20 is positioned longitudinally over the organ 100.This embodiment may be advantageous at least in allowing a physician tomonitor the condition of the transplanted organ from the time of surgerythrough recovery to determine the condition of the organ 100. Aphysician may use information about the condition of the organ to decideif any further intervention, such as drug treatment (such as antibioticsor immunosuppressants) or retransplantation may be required. This methodof monitoring may be advantageous at least in that it may minimizeprocedures to inspect the organ, enabling detection of organ dysfunctionat an early stage, which may allow therapeutic intervention prior toreversible damage, increase implant survival, decrease mortality rate(from infection, organ rejection), decrease the number of organs usedfor retransplantation, and the additional risk and cost ofretransplantation.

While the specification describes particular embodiments of the presentinvention, those of ordinary skill can devise variations of the presentinvention without departing from the inventive concept. For example, itwill be understood that the invention may also comprise any combinationof the embodiments described.

Although now having described certain embodiments of methods and devicesof a surgical drain, it is to be understood that the concepts implicitin these embodiments may be used in other embodiments as well. In short,the protection of this application is limited solely to the claims thatnow follow.

1. An implantable surgical drain for draining fluid from and sensing a condition of a surgical wound within a patient's body comprising: an elongated conduit having a drain lumen configured to be implanted within the surgical wound and to rest against but not penetrate the tissue within the surgical wound and a plurality of drain holes spaced along substantially the length of the drain lumen that are configured to drain fluid from the surgical wound; and at least one sensing element affixed to the elongated conduit and configured to sense a biochemical property of drained fluid within the drain lumen.
 2. The surgical drain of claim 1, wherein the elongated conduit is configured to drain blood, puss, bile or intestinal contents.
 3. The surgical drain of claim 1, further comprising a plurality of sensing elements configured to sense a plurality of biochemical properties.
 4. The surgical drain of claim 1, wherein the biochemical property is selected from the group comprising: concentration, color, oxygenation, biochemical composition, or drug concentration.
 5. The surgical drain of claim 1, further comprising a display in communication with the at least one sensing element, wherein the display is configured to depict data corresponding to the biochemical property sensed by the at least one sensing element.
 6. An implantable surgical drain for draining fluid from and sensing a condition of a surgical wound within a patient's body comprising: an elongated conduit having a drain lumen configured to be implanted within the surgical wound and to rest against but not penetrate the tissue within the surgical wound and a plurality of drain holes spaced along substantially the length of the drain lumen that are configured to drain fluid from the surgical wound, the elongated conduit including a first position and a second position located within the drain lumen; a first transmitting element placed proximate to the first position, configured to deliver energy into the drain lumen; and a first sensing system placed proximate to the second position, configured to receive the delivered energy after it is modulated by a biochemical property of at least one substance within the lumen.
 7. The surgical drain of claim 6, wherein the first transmitting element and first sensing system are embedded within the conduit behind material that is optically transparent.
 8. The surgical drain of claim 6, wherein the first position and second position are located on substantially opposite sides of the drain lumen.
 9. The surgical drain of claim 6, wherein the lumen includes a third position and a fourth position, further comprising: a second transmitting element configured to deliver energy to the lumen proximate to the third position; and a second sensing system configured to receive energy proximate to the lumen fourth position.
 10. The surgical drain of claim 9, further comprising a processing system in communication with the first and second sensing systems configured to compare a difference between the energy detected by the first and second sensing systems.
 11. The surgical drain of claim 9, further comprising a third sensing system configured to sense a different biochemical property than the first sensing system.
 12. The surgical drain of claim 11, wherein the biochemical property is selected from the group comprising: concentration, color, oxygenation, pH, biochemical composition, or drug concentration.
 13. The surgical drain of claim 11, further comprising a display in communication with the second sensing system, wherein the display is configured to depict data corresponding to the biochemical property sensed by the second sensing system.
 14. A method of draining fluid from and monitoring the condition of a surgical wound within a patient's body comprising: implanting a surgical drain having a drain lumen and a plurality of drain holes spaced along substantially the length of the drain lumen within the surgical wound such that substantially the length of the drain lumen rests against tissue within the surgical wound and oriented so as to drain fluid from the surgical wound to be monitored; sensing by a first sensing system affixed to the surgical drain of a biochemical property of a substance within the drain lumen over time; receiving information from the first sensing system regarding the sensed biochemical property within the drain lumen; and monitoring the information received from the sensing system to evaluate the condition of the tissue over time.
 15. The method of claim 14, further comprising transmitting energy within the drain lumen and receiving energy with the first sensing system.
 16. The method of claim 14, further including processing the information received from the first sensing system.
 17. The method of claim 16, further including displaying information received from the first sensing system.
 18. A method of monitoring substances within a surgical wound in a patient's body comprising: implanting a surgical drain having a drain lumen and a plurality of drain holes spaced along substantially the length of the drain lumen so as to rest against a substantial length of tissue within the surgical wound, wherein the plurality of drain holes are spaced along substantially the length of the lumen and are configured to drain fluid from the surgical wound; sensing by a first and a second sensing system affixed to the drain a biochemical property of at least one substance within the drain lumen over time; receiving information from the first and second sensing systems regarding the sensed biochemical property within the drain lumen; and monitoring the information received from the first and second sensing systems to evaluate the condition of the tissue over time.
 19. The method of claim 18, further comprising processing information from the first and second sensing systems to compare a difference in information received from the first and second sensing systems.
 20. The method of claim 18, further comprising processing information from the first and second sensing systems to compare a difference in information received from the first and second sensing systems proximate to different positions along the drain lumen. 